PROJECT SUMMARY Hispanic populations in the United States (US) continue to be seriously impacted by persistent health disparities. According to the 2017 Monitoring the Future Study, Hispanic adolescents had the highest rates of use of most illicit drugs compared to other ethnic groups. When considering differential risks among Hispanics, US-born youth in low-income first-generation immigrant families are at high risk for experiencing poverty, discrimination, and barriers to access services. These adolescents can also be exposed to deleterious parent- youth cultural conflicts, which may increase their risk for behavioral problems, including the use of alcohol and other drugs. Contextual stressors also have a negative impact on the quality of parenting practices of immigrant parents, with associated deleterious consequences for their adolescent children. Although parent training (PT) interventions constitute the gold standard for strengthening parenting practices that are effective protective factors in the lives of adolescents, the availability of efficacious culturally adapted PT interventions in underserved Hispanic communities remains scarce throughout the US. Thus, there is an urgent need in the implementation science (IS) field to identify implementation strategies aimed at addressing service gaps affecting Hispanic populations. A promising alternative consists of relying on third sector organizations, such as faith-based organizations, to integrate prevention programs in underserved communities. The current R34 investigation will consist of the implementation and modest refinements of a culturally adapted version of the evidence-based PT intervention known as GenerationPMTO. Our rationale is that implementing efficacious prevention interventions in faith-based organizations constitutes a key alternative to address service barriers experienced by underserved populations. We also propose that by training lay members of target communities as prevention interventionists, the sustainment of prevention programs can be significantly enhanced. This study has relevance as we focus on a population that remains understudied in the IS field. Our research team is composed of the largest faith-based organization serving Hispanics in Travis County, Texas, as well as a core research team affiliated with the University of Texas at Austin, expert IS consultants, and community- based organizations serving Hispanic populations. The research aims of this R34 investigation are: (a) To implement a pilot study aimed at refining the CAPAS-Youth curriculum and study procedures, (b) to implement a randomized controlled trial, aimed at empirically testing the efficacy of the CAPAS-Youth intervention with first-generation low-income Hispanic families in Travis County, (c) to measure barriers and facilitators associated with the implementation of the CAPAS-Youth prevention intervention in the target context, and (d) to measure relevant implementation outcomes to inform a future R01 effectiveness trial. The investigation has high